We have devised a procedure to encapsulate any desired enzyme within erythrocyte. We hope that this procedure will be useful for the treatment of cancer especially, asparaginase-sensitive leukemias because 1-asparaginase will be protected from circulating antibodies. We hope that this procedure will also be useful for enzyme therapy of certain sphingolipidoses such as Gaucher's disease because the red blood cell, suitably activated for destruction, will be taken up by the liver, spleen, and possibly kidney, thus introducing the missing enzyme into the affected cells.